This invention relates to an improvement in lighting fixtures, and more particularly to a lamp with an improved means of adjustment to provide efficient, glare-free illumination for reading without shining in one's eyes, or to provide mostly upward indirect illumination.
The most common kind of lighting is over the shoulder of a seated person, with a shade to keep light from shining directly in the eyes of that person or of anyone else in the room. The most common method of adjustment is to tilt a shade to provide task lighting, but not so much as to shine in one's eyes. This generally involves rotation around a harp wire, which involves an extra step: turning the lamp so that the shade tilts in the intended direction. Such handling soils a shade, which is not easily cleaned. Fuller's lamp (U.S. Pat. No. 2,857,509) has a vertically adjustable shade, but the means of adjustment is more complex than that of the present invention, which involves moving the bulb by its cord. Ohm and Godfrey (U.S. Pat. Nos. 2,231,137 and 2,113,134) each moved the bulb vertically by its cord, but not with respect to a shade, and neither provides a convenient means of moving the cord that is comparable to that of the present invention.
Illumination should also be glare-free and efficient in terms of lumens per watt, both of which can be achieved by lining the shade with reflective material. Reducing glare is a function of angular dispersion of the effective light source with respect to the task, and can be achieved with a large reflective shade that is not circular around the bulb. Also, a reflective lining increases the effectiveness of adjusting the bulb vertically with respect to the shade, as discussed above, because as the bulb is lowered, the shift toward lateral illumination is much greater for reflected than for direct rays.
Mounting a lamp on a wall is advantageous because end tables can be put to better use, and floor lamps are expensive and heavy. In mounting, at least two points should be attached for stability. Positioning two attachments on a wall involves the difficulty of determining verticality and distance simultaneously, so the invention provides a simple instrument to do this.
It is also desirable to be able to change the covering on a shade for any decor, and to keep the cord neat. Lamp manufacture tends to be labor intensive and to use expensive materials, so it is desirable to find ways to reduce these costs. Finally, a mass produced lamp should be compact for shipment; therefore, this invention is designed so that all parts can be packed within the shade.